K8055 PWM build problem?

Kits PC Related Projects
1

I have built the K8055 circuit and it works with the demo software. All digital outputs work well and the analogue outputs are great however the PWM outputs seem to hovver around the 50% mark and will not move on the demo software. I figure I have a build problem but cannot figure out where.

One thing I noticed was that the final capacitor on the build was a small blue ceramic one rather than the square one as per the picture on the instructions. I checked the values and as far as I can tell they were the same. This could be a red herring.

Any advice will be warmly received.

2

[quote]All digital outputs work well and the analogue outputs are great however the PWM outputs seem to hovver around the 50% mark and will not move on the demo software.[/quote]The analog output is generated by filtering the PWM output. If the analog output value changes then also the PWM should change.

The PWM output is an open collector transistor output. You need to put there a pull-up resistor from the output to external (+) voltage.